Funerals, memorials, tombstones, monuments, days of rememberance, wakes, Memorial Day, flowers on a gravestone, books dedicated "in loving memory", a place set at Thanksgiving for a long departed family member - it would seem that all these forms of rememberance are more for the benefit of the living than the dead. And yet, the Restless benefit greatly from those who remember them - quite literally. The emotional energy of the living , as expressed in their thoughts, words and deeds, is transmitted into a wraith's Lifeweb.
Memoriam represents the amount of "emergency" Pathos that a wraith can siphon per session. In dire straits, a wraith who has already recieved her Pathos for the chapter can roll her Memoriam rating (difficulty 8). The number of successes equals the amount of Pathos points she instantly gains. If this roll botches, her Memoriam rating reduces by one: the dead can only steal so much before the memories of the living diminish.
Note that famous people transcend the 1 to 5 scale for Memoriam: Elvis for example, has an 8 Memoriam (if he is indeed departed...).
Only one person remembers you well.
A few close friends remember you.
Your family remembers you fondly.
A large organization (the Rotarians, a gang, a church congregation, a small cult) remembers and reveres you.
A building or some other permanent public facility has been dedicated to you; people use your name on a daily basis.